Drugs online research references
J Clin Invest. 1989 May;83(5):1758-61.
Specific binding of endothelin on human vascular smooth muscle cells in culture.
Clozel M, Fischli W, Guilly C.
Pharmaceutical Research Department, F. Hoffmann-La Roche & Co., Ltd., Basle, Switzerland.
Endothelin is a newly discovered, potent vasoconstrictor peptide secreted by endothelial cells. The binding of endothelin was studied on cultured human vascular smooth muscle cells obtained from umbilical veins. A single specific binding site for 125I-endothelin was identified, with an apparent Kd of 126 pM and a maximal binding capacity of approximately 10,000 sites per smooth muscle cell. At room temperature the binding was saturable, reached equilibrium at 2 h (using 20 pM endothelin), and was slowly and only partially reversed by unlabeled endothelin. The calcium antagonists nifedipine, nicardipine, and diltiazem did not compete for the same binding site. Conditioned medium from cultured human umbilical vein endothelial cells inhibited the binding of 125I-endothelin dose dependently. This effect was antagonized by anti-endothelin antiserum. We conclude that human umbilical vein smooth muscle cells possess specific binding sites for endothelin, and that human endothelial cells secrete an endothelinlike material.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2651480&dopt=Abstract
Br J Clin Pharmacol. 1994 Dec;38(6):505-12.
Interaction between endothelin and vasodilators in the human internal mammary artery.
He GW, Yang CQ, Mack MJ, Acuff TE, Ryan WH, Starr A.
Albert Starr Academic Center for Cardiac Surgery, St Vincent Heart Institute, Portland, Oregon 97225.
1. The internal mammary artery (IMA) is the primary choice as an arterial graft for coronary artery bypass surgery. Endothelin (ET) has been recently measured with an increased release after cardiopulmonary bypass for coronary artery bypass grafting. Threshold concentrations of ET-1 have been found to amplify specifically contractions induced by noradrenaline and serotonin. This study was designed to investigate the effect of glyceryl trinitrate (GTN) and calcium antagonists on ET-1 contraction in the human IMA. 2. Human IMA segments taken from 21 patients undergoing IMA-coronary artery bypass grafting were mounted in an organ bath under the physiological pressure determined from their own length-tension curves. Four ring segments were allocated into four groups. One served as a control and the others were treated with GTN (10, 100 nM, or 30 microM) for 5 min or nifedipine (20 or 200 nM, or 30 microM) for 25 min before concentration-contraction curves to ET-1 were established. In separate experiments, the concentration-relaxation curves to GTN or nifedipine were established in the IMA rings precontracted with ET-1 (10 nM). 3. Pretreatment of IMA with GTN for 5 min did not alter the ET-1-induced contraction. Pretreatment with 20 or 200 nM of nifedipine slightly but not significantly, altered the maximum contraction induced by ET-1. Higher concentrations (30 microM) significantly reduced the maximum contraction force (P = 0.008). On the other hand, GTN caused 76.44 +/- 6.35% relaxation in ET-1-precontracted IMA. In contrast, the nifedipine-induced relaxation was difficult to establish due to unsustained contraction to ET-1.(ABSTRACT TRUNCATED AT 250 WORDS)
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7888288&dopt=Abstract
J Hypertens Suppl. 1994 Jan;12(1):S21-6.
Vascular effects of endothelin-1 in humans and influence of calcium channel blockade.
Kiowski W, Linder L, Erne P.
Department of Medicine, University Hospital, Basel, Switzerland.
AIM: To investigate the effects of brachial artery infusions of endothelin-1 on forearm blood flow in normal healthy volunteers. METHODS: Brachial artery cannulation was used for a direct assessment of blood pressure and for intra-arterial regional drug infusions. Drug-induced forearm blood flow changes were measured by venous occlusion plethysmography. RESULTS: Low-dose endothelin-1 infusions resulted in a significant increase in forearm blood flow, indicating vasodilation, which was significantly attenuated by cyclo-oxygenase inhibition using aspirin. High-dose endothelin-1 infusions resulted in transient vasodilation, followed by dose-dependent and long-lasting vasoconstriction. In the human forearm the vasoconstrictor potency of endothelin-1 was approximately 10-15 times greater than that of norepinephrine. Maximal cyclic GMP-dependent vascular muscle relaxation, after muscarinergic stimulation by acetylcholine (endothelium-dependent) or after infusion of sodium nitroprusside (endothelium-independent), did not prevent endothelin-1 induced vasoconstriction. However, calcium channel blockade by brachial artery infusions of maximally vasodilating doses of either verapamil or nifedipine not only abolished the endothelin-induced vasoconstriction but also unmasked the vasodilator potency of high-dose endothelin-1 infusions. The infusion of lower doses of nifedipine indicated that endothelin-1 induced vasoconstriction was reversed by plasma concentrations estimated to be in the therapeutic range. CONCLUSIONS: These results demonstrate a dual action of luminally applied endothelin-1 in human resistance vessels in vivo, consisting of transient initial vasodilation followed by pronounced vasoconstriction, and suggest that blockade of voltage-operated calcium channels can effectively counter the vasoconstrictor effects of endothelin-1.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8207561&dopt=Abstract
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